An air-cleaning cartridge of the above-described class has become known from U.S. Pat. No. 4,193,966. The prior-art air-cleaning cartridge has individual inserts arranged in a radiate pattern, which are accommodated in a cylindrical cartridge housing and whose intermediate spaces are packed with a carbon dioxide-binding chemical. The inserts are made of solid, metallic material and have legs extending in a radial direction, which converge in a center and whose free ends are in contact with the wall of the cartridge housing.
It is disadvantageous in the prior-art air-cleaning cartridge that the intermediate spaces of the legs can be packed only at a limited packing density because of the rigidity of the legs, as a result of which such air-cleaning cartridges are not resistant to vibrations and shocks during operation. Resistance to vibrations and shocks means in this connection that the chemical must not be "crushed" during the use of the apparatus when, e.g., a gas mask and breathing equipment is worn by a person for several years for a possible emergency use in underground mining. In addition, only radial heat conduction within the air-cleaning cartridge is possible with an insert of the above-described class. If a substance that binds carbon dioxide and generates oxygen, e.g., potassium peroxide, is used as the chemical packing, good heat distribution or heat storage capacity by the insert in both radial direction and circumferential direction, rather than heat conduction in the radial direction alone is necessary for uniform breathing from the air-cleaning cartridge.
Swiss Patent No. CH-PS 207,614 discloses an air-cleaning cartridge in which uniform packing density is achieved by packing a wire screen strip with a chemical and subsequently winding it helically. To guide the flow within the air-cleaning cartridge, ribs, which may have a zigzag or corrugated design, are provided within the wire screen strip. This is the to lead to uniform heat distribution and breathability of the air-cleaning cartridge.
It is disadvantageous in the prior-art air-cleaning cartridge that the use of a wire screen strip is expensive, and packing the wire screen strip cannot be carried out at a favorable cost in mass production. In addition, the amount of chemical with which the air-cleaning cartridge can be packed is reduced by the volume of the wire screen strip. However, since the external dimensions of the air-cleaning cartridges have been extensively specified by standardization, inserts must be designed with the smallest possible volume. In regard to dynamic load-bearing capacity, an air-cleaning cartridge with a wire screen strip as the insert has only limited shock resistance, because the wire screen strip may undergo permanent deformation under the effect of loads, as a result of which the uniform packing density is destroyed.